As is widely known, there are analog and digital methods for high frequency measuring of magnetic properties. In the analog method, it is not possible to store and process the measured data in a digital computer since the data, of magnetic properties, which is displayed as voltage by the general purpose oscilloscope, can only be read. However in case of high frequency measurement, the data measured has to be recorded within a short period because rapid heat emission of a sample leads to measurement errors. Therefore, in the analog method, the high frequency measurement of the above materials over a few KHz frequency is really difficult due to an impossibility of storing and controlling the data through a computer.
For the above reasons, the high frequency measurement of the magnetic properties such as a core-loss and a hysteresis curve of the materials mentioned is almost always performed by the digital method.
The conventional digital method mainly consists of the following measurements:
measuring the magnetic properties of the materials by mounting the interface card of A/D converter and high speed data bus respectively to a computer; PA1 measuring the magnetic properties using an oscilloscope; PA1 recording a waveform by using an exclusive digitizer; PA1 measuring only core-loss by allowing the power-meter to have digital function; and PA1 measuring the core-loss by using the high speed A/D converter circuit and the signal generator.
Both of the measuring methods of (1) mounting the interface card of the A/D converter and high speed data bus to a computer and (2) recording a waveform by using the exclusive digitizer have substantially a high horizontal resolution, but they have difficulty when measuring in a high frequency over the MHz range, as well as a disadvantage due to the higher expense of a system.
Also the digitized power-meter has a disadvantage, wherein it cannot measure the waveform of a magnetic hysteresis curve, even though it is able to measure a core-loss up to the range of several hundred KHz range by using the A/D converter to digitize the received signal.
The method utilizing a digital oscilloscope obtains a magnetic hysteresis curve by initially recording the received waveform in the digital oscilloscope and subsequently processing it in a computer. The method using the single measuring group containing a high speed A/D converter circuit and a signal generating circuit obtains only necessary select functions among the combined functions between an oscilloscope and a computer. Therefore in the measurement of a core-loss and a magnetic hysteresis curve over MHz frequency range, both of these methods are substantially adopted.